lithium-fluoride and Breast-Neoplasms

Lithium fluoride (TLD-700) dosimeters were used to measure exit surface absorbed doses in external beam radiotherapy using an automated TLD reader. Delivered tumour absorbed doses were derived from these measurements for head and neck, pelvis and breast treatments. For the head and neck treatments (first fraction only), the mean percentage difference between prescribed and delivered tumour absorbed doses was -0.15 +/- 3.0% (+/- 1 SD), for the pelvic treatments -0.83 +/- 2.8% and for the breast treatments +0.26 +/- 2.9%. The spread of results is approximately +/- 3% (+/- 1 SD). This is comparable with the estimated uncertainty in a single TLD absorbed dose measurement in phantom (+/- 2%; +/- 1 SD). Thus, ICRU recommended tolerances for absorbed dose delivery of +/- 5% may not be unequivocally detectable using this method. An action level of +/- 10% is suggested, allowing investigation of possible gross errors in treatment delivery at an early stage, before the course of treatment has progressed to a point at which absorbed dose compensation is impossible.

Topics: Breast Neoplasms; Evaluation Studies as Topic; Fluorides; Head and Neck Neoplasms; Humans; Lithium Compounds; Pelvic Neoplasms; Pilot Projects; Radiation Dosage; Radiotherapy Planning, Computer-Assisted

The incidence of secondary cancers in the contralateral breast after primary breast irradiation is several times higher than the incidence of first time breast cancer. Studies have shown that the scatter radiation to the contralateral breast may play a large part in the induction of secondary breast cancers. Factors that may contribute to the contralateral breast dose may include the use of blocks, the orientation of the field, and wedges. Reports have shown that the use of regular wedges, particularly for the medial tangential field, gives a significantly higher dose to the contralateral breast compared to an open field. This paper compares the peripheral dose outside the field using a regular wedge, a dynamic wedge, and an open field technique. The data collected consisted of measurements taken with patients, solid water and a Rando phantom using a Varian 2300CD linear accelerator. Ion chambers, thermoluminescent dosimeters (TLD), diodes, and films were the primary means for collecting the data. The measurements show that the peripheral dose outside the field using a dynamic wedge is close to that of open fields, and significantly lower than that of regular wedges. This information indicates that when using a medial wedge, a dynamic wedge should be used.

Topics: Breast; Breast Neoplasms; Evaluation Studies as Topic; Female; Fluorides; Humans; Incidence; Lithium Compounds; Models, Structural; Neoplasms, Radiation-Induced; Neoplasms, Second Primary; Particle Accelerators; Radiation Protection; Radiotherapy Dosage; Radiotherapy, High-Energy; Scattering, Radiation; Thermoluminescent Dosimetry

Breast irradiation in the lateral decubitus (LD) position is a technique used at the Institut Curie for more than 30 years in the breast-conserving management of patient with breast cancer. This technique is described in detail in this article. The patient's position allows the breast to flatten over a support, hence providing a rather homogeneous thickness throughout the treated volume. Dose at mid-thickness on the beam axis can be easily determined from entrance and exit dose measurements. Disadvantages and advantages of the LD technique are discussed. We presently recommend this technique for patients with large breasts (more than 6 cm thickness in LD position).

Topics: Breast Neoplasms; Cobalt Radioisotopes; Dose-Response Relationship, Radiation; Female; Fluorides; Follow-Up Studies; Humans; Lithium; Lithium Compounds; Methods; Posture; Radiotherapy Dosage; Thermoluminescent Dosimetry; Tomography, X-Ray Computed

In 23 cases of breast cancer treated conservatively using external beam and interstitial radiotherapy, lithium fluoride thermoluminescent dosimetry has been used to measure the radiation dose received by the breast tissue at depth. Thirty-six investigations were made using a number of lithium fluoride micro-rods for each investigation. Three results could not be analysed because of measurement problems in two and insufficient information in one. Twenty-eight results were obtained at a depth in tissue greater than the build-up zone, 23 of the 28 falling within +/- 5% and 27 of the 28 falling within +/- 10% of the computer-calculated prescribed dose. Of five results obtained within the build-up zone, two fell within +/- 5% and four within +/- 10% of the prescribed dose.

Topics: Brachytherapy; Breast Neoplasms; Fluorides; Humans; Lithium; Lithium Compounds; Methods; Radiotherapy Dosage; Thermoluminescent Dosimetry